A Maryland National Bank employe, kidnaped at gunpoint in front of her husband and two young sons in their Harford County mobile home, was released unharmed yesterday after her employers agreed to pay $250,000 to her abductor.

The money was recovered minutes after 28-year-old Andrea Bowling was released on a Baltimore County street, and late yesterday a Baltimore man was arrested in connection with the abducation.

Bowling was held for 11 hours by a man, who had knocked at the door Wednesday night, asking about the "for sale" sign in the window. Bowling offered herself as a hostage after the man threatened to take one of her sons instead.

Three Maryland State Highway Administration inspectors were originally picked up as suspects after they hauled up the rope attached to the ransom money, which was in a cloth bag dangling from a Baltimore County bridge, and carried the bat toward their truck according to the FBI. The three men were released after five hours of questioning when they were determined to be bridge inspectors.

Late yesterday the FBI and Baltimore County police arrested Ronald Joseph Hackett, 40, of Baltimore County and charged him in connection with the extortion plot, according to an FBI spokesman.

Bowling, described by neighbors as a assistant bank manager, was taken from her mobile home moments after a man, holding a shotgun and pistol, bound her husband, Jerry and 8-year-old son, Jerry Jr. with tape.

One neighbor said she had learned that the gunman had said he wanted to take ''little Jerry but little Jerry yelled 'no'

Then, according to the neighbor, the gunman said, "You'll live to regret this."

Jerry Jr. Freed himself from the tape and ran to a neighbor's mobile home, screaming, "Come help my dad. He's being robbed," according to the neighbor, Carol Ritter.

Meanwhile, Jerry Bowling, gun in hand, jumped into his car and took off after his wife and the gunman, according to Ritter's husband James.

The Bowlings' younger son, Jeremiah, 2, remained asleep on the living room couch while the abduction occurred, according to Carol Ritter.

Within minutes Bowling, in his car, and several carloads of state policemen arrived back at the mobile home village in Edgewood, about 20 miles northeast of Baltimore.

At midnight Bowling's boss, Ralph Wood, was telephoned by a male caller who told Wood he was holding Bowling and wanted a "large sum of money," according to state police spokesamn William Clark.

Wood had been called at home last week by a man who threatened him and made a "veiled suggestion of possible extortion," according to Clark.

At about 3 a.m. Thursday, Wood received a second call, telling him to place about $250,000 in a briefcase and go to a Baltimore County phone booth to await further instructions, Clark said.

The money was taken to the booth, and after a note was found there, the money, in the briefcase inside a cloth bag, was taken to the Back River bridge in Baltimore County and tied to a railing there, according to authorities.

FBI agents and Baltimore County police officers then kept watch on the bridge for several hours.

At about 9 a.m., several miles away, Bowling was dropped off on a Baltimore County street, and ran to a stranger's home seeking help. The woman who answered the door called county police.

A few minutes later, authorities watching the bridge saw a truck belonging to the State Highway Administration stop at one end of the bridge. Three men got out and walked to the center of the bridge, and two of them pulled up the rope, looked at the bag and then dropped it back, according to an FBI spokesman.The three men conferred, then returned to the rope, pulled it up, took the briefcase containing the money from inside the bag and walked off with it, the spokesman said.

The men, later identified as bridge inspectors, were immediately arrested, the spokesman said. They were interviewed for several hours and finally released.

At about 5 p.m. Ronald Hackett was arrested at a Baltimore County shopping center. He was charged with violation of the Hobbs Act, a federal extortion statute, according to the FBI.

The FBI spokesman refused to reveal what information led to Hackett's arrest.

Bowling and her husband were questioned and then taken back to their mobile home, where they remained secluded and guarded by police late yesterday.

Their children spent the night at the Ritter home, and Carol Ritter said Jerry Jr. awoke often from nightmares.

Baltimore County Police Maj. Francis T. Hutson said that police were investigating last week's threatening calls to Wood when they learned of Bowling's abduction. He said he believed the two incidents are related.